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The dilution effect shows the idea that an individual in a large group will have a reduced risk of predation compared to an individual in a small group or a solitary individual. Hence the risk is ‘diluted’ among the other members in a group. It is important to note however; this effect only occurs where predators are unable to capture all ...
A dilution effect is seen when animals living in a group "dilute" their risk of attack, each individual being just one of many in the group. George C. Williams and W.D. Hamilton proposed that group living evolved because it provides benefits to the individual rather than to the group as a whole, which becomes more conspicuous as it becomes larger.
This effect has been partly attributed to stress, although hydrodynamic factors were considered more important in this particular study. [6] The calming effect of being with conspecifics may thus provide a social motivation for remaining in an aggregation. Herring, for instance, will become very agitated if they are isolated from conspecifics. [7]
The researchers concluded that subjects were less likely to help the greater the number of bystanders, demonstrating the bystander effect. [ 39 ] [ 7 ] The bystander effect [ 22 ] is a specific type of diffusion of responsibility—when people's responses to certain situations depend on the presence of others.
In it Burnet expanded the ideas of Talmage and named the resulting theory the "clonal selection theory". He further formalised the theory in his 1959 book The Clonal Selection Theory of Acquired Immunity. He explained immunological memory as the cloning of two types of lymphocyte. One clone acts immediately to combat infection whilst the other ...
His theory states that multicellular organisms consist of germ cells that contain and transmit heritable information, and somatic cells which carry out ordinary bodily functions. [ 1 ] [ 2 ] In the germ plasm theory, inheritance in a multicellular organism only takes place by means of the germ cells: the gametes , such as egg cells and sperm cells.
One of the most important features of chemostats is that microorganisms can be grown in a physiological steady state under constant environmental conditions. In this steady state, growth occurs at a constant specific growth rate and all culture parameters remain constant (culture volume, dissolved oxygen concentration, nutrient and product concentrations, pH, cell density, etc.).
Charles Darwin considered the evolution of eusociality a major problem for his theory of natural selection. In The Origin of Species, he described the existence of sterile worker castes in the social insects as "the one special difficulty, which at first appeared to me insuperable and actually fatal to my whole theory". In the next paragraph of ...